The U.S. Embassy said Saturday it evacuated non-essential staff from Beirut for security reasons as Lebanon, with rival Moslem and Christian Cabinets, drifted further toward partition and the possibility of renewed civil war.

The evacuations were ordered as a precaution as the leader of the military Cabinet appointed by former President Amin Gemayel scrambled to head off a political crisis described as the worst in the nation's history.Army commander Maj. Gen. Michel Aoun, the Maronite Christian appointed by Gamayel to head the six-member interim Cabinet, and Selim Hoss, the Moslem premier of the outgoing Cabinet, both have claimed the right to run the troubled nation since President Amin Gemayel left office midnight Thursday under a constitutional deadline.

Unknown culprits fired a rocket Saturday into a Syrian-guarded hotel where the son of another presidential hopeful is staying, hitting the building and starting a fire, police said.

The hotel has been heavily guarded by Syrian troops since the son of pro-Syrian politician Suleiman Franjieh, Robert, took up residence at the building to rally support for his father's candidacy for the presidential elections.

Christian officials have accused the Syrians of placing a Christian parliamentarian, Farid Serhal, under house arrest at the hotel.

U.S. Embassy spokesman James Magmor said security concerns brought on by the sudden destabilization led to the decision to cut staff.

"In view of the uncertainty of the situation, it was decided to let a small number of non-essential personnel leave," Magmor said in a telephone interview.